Hot-rolled rails at a high temperature above the austenite transformation temperature range are, in some cases, subjected to forced cooling as heat treatment to ensure desired qualities such as hardness required for the rail head. In other words, the hot-rolled rails are cooled with a cooling medium sprayed onto the rails. Normally, the forced cooling. (hereinafter also referred to as heat treatment cooling) in a heat treatment process is performed until the microstructure of the rail head is completely transformed from austenite to pearlite or bainite, and the cooling stops when the temperature drops down to about 400° C. to 500° C. The heat treatment cooling on rails is normally performed on both head and foot of the rails in an upright position. The heat treatment cooling on the head is performed to ensure the qualities such as hardness as described above, whereas the heat treatment cooling on the foot is performed to prevent upward and downward warp of the rails caused by heat stress occurring due to a temperature difference between the head and the foot.
Various techniques are disclosed for obtaining rails with smaller warp while ensuring the qualities for the rail head. For example, Patent Literature 1 discloses a method for cooling a rail by which the rail head is cooled with a cooling medium sprayed thereon in an amount that satisfies a target for material quality, while the rail foot is cooled with a cooling medium sprayed thereon in an amount adjusted to straighten a curved shape of the rail. Patent Literature 2 discloses a method in which cooling on the foot starts before cooling on the head starts. Patent Literature 3 discloses a method in which cooling on the head and cooling on the foot are simultaneously started but the head is more strongly cooled than the foot to minimize the warp.